1. Field of the Invention
The present invention relates generally to a method of manufacturing vehicle chassis structures for motor vehicles. More particularly the present invention relates to a method of manufacturing rear structures for motor vehicles in a manner that allows assembly of multiple body configurations on a single assembly line.
2. Disclosure Information
In conventional motor vehicles, suspensions found on sedans generally include rear shock absorbers or struts mounted vertically for a variety of reasons. The upper ends of shock absorbers and strut assemblies are attached to structure usually located behind the rear seats. The desirable interior volume of the trunk is only minimally impacted by this design, as the trunk region immediately behind the rear seats is difficult to access. On the other hand, vehicles having different body configurations, such as sport utility vehicles, station wagons and vans, all seek to provide low, flat load floors. Additionally, consumers of these vehicles place a premium on total cargo volume as well as on the width of the load floor. For this reason, vehicle manufacturers have provided unique rear suspensions for such vehicles, tilting the rear shock absorbers from the usual vertical orientation so as to reduce their overall vertical intrusion in the vehicle while maximizing the load floor width.
In the normal course of designing and building motor vehicles, it is desirable to build multiple body configurations from a single vehicle platform. This allows common manufacturing equipment and processes to build a greater variety of related vehicles. To date, manufacturers have not been able to gain these efficiencies when constructing the rear structure for motor vehicles having a sedan style rear suspension and a unique wagon/van/SUV style rear suspension. The sedan construction has generally included relatively low and inboard frame rail members, vertically intrusive wheelhouse inners for supporting vertical shock or strut mounts, as well as a deeply drawn floor pan to allow for a deep trunk.
In contrast, the wagon/van/SUV configurations require relatively high and outboard frame rail members to allow the shock absorber to be tilted under the frame rail member. Additionally, these body configurations require unique attachment structure for the upper end of the shock absorber, as well as unique, non-vertically intrusive, wheelhouse inner members to provide maximum load floor width and finally a higher floor pan for mounting the upper end of the tilted shock absorbers. From this, it can be concluded that there are considerable differences in the structure of these two configurations.
To accommodate assembly of these vastly different vehicle structures, assembly plants must be provided with separate body assembly lines. The location of the welds between the floor pan assembly to the frame rails are unique, as are the welds between the wheelhouse inner member and the floor pan and quite often, even the quarter panel. Other equipment, including fixtures, sealers etc. must be uniquely configured for each of the unique body structures to accommodate the varying vehicle configurations, all at considerable expense to manufacturers and ultimately consumers.
It would be desirable to overcome the aforenoted difficulties with a method of manufacturing a rear vehicle structure using common assembly equipment and facilities, thus allowing manufacturers to make multiple body configurations on a common assembly line, which has not previously been available.